HP StorageWorks 4000 Understanding Compaq StorageWorks RAID Array 4000 and Inf - Page 3

Understanding Compaq StorageWorks RAID Array 4000 and Infrastructure Cabling 3 Understanding Fibre Channel Transmission Note: This paper includes the terms fibre and fiber. Fibre is the international spelling that refers to the Fibre Channel Standards that include both optical and copper media. Fiber refers to the optical media used to implement Fibre Channel. Fibre Channel uses lasers2 to achieve gigabit data transmission rates. The ones and zeros used to convey information are generated by turning a laser on and off. The receiver detects these bursts of light and converts them to electrical signals. Lasers used in Fibre Channel transmit light in two wavelength ranges: • Shortwave, 770 to 860 nanometers • Longwave, 1,270 to 1,355 nanometers Optical fiber cable is the medium used in RA4000 solutions. Characteristics of optical fiber cable are: • High bandwidth. • Transmits data over long distances. • Increased data transmission reliability. • Immunity to electrical noise. • Does not radiate energy. Optical fiber cable is categorized as either multi-mode3 or single-mode. In Figure 1, the diameter of a multi-mode fiber is large enough to allow multiple streams of light to travel on different paths from the transmitter to the receiver. Shortwave lasers are used with multi-mode fiber to transmit data up to 500 meters. Figure 1. Multi-mode fiber cable 2 Laser technology uses fiber optic media only. 3 Mode means path. ECG02030699A